High energy metal forming apparatus



Dec. 18, 1962 J. P. ORR ETAL 3,068,822

HIGH ENERGY METAL FORMING APPARATUS Filed July 51, 1959 2 Sheets-Sheet 1 14 74 1o 92 16 64 K as I'M as I FLOYD FXW 42 6:2 )0 50 e264 Q 626 M40 44 o 24 I 60 x 4 u a: i I 1 I1 26 58 a hr;- 6 I8 Dec. 18, 1962 J. P. ORR EI'AL 3,068,822

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. mvENToRs. FLOYD *Agcox .mm-zs P"."ORR BY ilnite rates Patent G 3,068,822 HGH ENERGY FORMING APPARATUS lames P. Orr, Lakeside, and Floyd A. Cox, San Diego,

Calif., assignors to Ryan Aeronautical (30., San Diego,

Calif.

Filed July 31, 195), Ser. No. 830,937 1 Claim. (Cl. 113-44) The present invention relates generally to metal working and more particularly to high energy metal forming apparatus.

The primary object of this invention is to provide appara-tus in which metal parts are formed by a high energy impulse, such as an explosion, the parts being formed over simple dies without the use of matching male and female die blocks.

Another object of this invention is to provide a high energy forming apparatus in which the explosion is con tained within a pressure vessel, so that the operation can be performed safely in restricted surroundings.

Still another object of this invention is to provide a high energy forming apparatus in which the parts are formed in an enclosed cavity which is evacuated of air to avoid air pockets or bubbles in the finished articles.

A further object of this invention is to provide a high energy forming apparatus which is capable of forming several different parts simultaneously.

Finally, it is an object to provide a high energy forming apparatus of the aforementioned character which is simple, safe and convenient to operate and which Will give generally eflicient and durable service with consistent results.

With these and other objects definitely in view, this invention consists in the novel construction, combination and arrangement of elements and portions, as will be hereinafter fully described in the specification, particularly pointed out in the claim, and illustrated in the drawings which form a material part of this disclosure, and in which:

FIGURE 1 is a vertical sectional view of the apparatus as taken on the line 11 of FIGURE 2;

FIGURE 2 is a sectional view taken on the line 22 of FIGURE 1; and

FIGURE 3 is an enlarged fragmentary sectional view taken on the line 33 of FIGURE 2.

Similar characters of reference indicate similar or identical elements and portions throughout the specification and throughout the views of the drawings.

Apparatus representative of that required to carry out forming according to the concepts of the present invention may include abed plate which is secured to a floor, or preferably in a shallow pit 12, said bed plate being held in place by anchor bolts 14 and nuts 16. On the bed plate is a base block 18 seated on a plurality of studs 20 extending upwardly from the bed plate 10, and secured by nuts 22, said base block having a chamber or cavity 24 in the upper portion thereof. The upper face of the base block 18 surrounding the cavity 24 is finished smooth and flat and comprises a seat face 26. Inside the cavity 24 are fixed various die blocks, as indicated at 28 and 30, said die blocks being shaped to conform to the contours of the parts to be formed thereon. Several difierent die blocks may be installed according to the size of the cavity, the size and shape of the die blocks not being critical, except that the upper faces thereof will ordinarily be slightly below the seat face 26, as in FIGURE 1. The die blocks 28 and 30 may be secured by suitable bolts, retaining pins, or the like, not illustrated, according to requirements.

Mounted above the base block 18 is a pressure dome 32 comprising a high strength cylindrical vessel having REE a closed upper end 34 with a head portion 36, said head portion having a large central aperture 38. The open lower end 40 of the pressure dome 32 has an outer flange 42 which conforms in size to the seat face 26. Fixed to and enclosing the lower end 40 is a flexible diaphragm 44 of thick rubber sheet or the like, the edge of said diaphragm being held under a retaining ring 46. Below the retaining ring 46 is a resilient sealing ring 48 which rests on and seals against the seat face 26. The sealing ring 48, retaining ring 46 and diaphragm 44 are secured by means of suitable screws 50 passing through all three pieces and threaded into the flange 42. The pressure dome 32 is centered on the base block 18 by guide pins 52 fixed into said base block and extending upwardly through slip fit holes 54 in the flange 42, the number of guide pins used depending on the size of the apparatus.

To ensure proper sealing, the pressure dome 32 is held by a plurality of eye bolts 56 pivotally attached to brackets 58 on the base block 18, said eye bolts fitting between paired lugs 60 extending from the flange 42 and secured by nuts 62 and washers 64. While the eye bolts provide an effective means for holding the pressure dome in position, it should be understood that other securing means, such as toggle clamps or the like, may be used if desired.

The pressure dome 32 is partially filled with fluid, indicated at 66, water being preferred for low cost and non-flammable properties although other fluids can be used. The head portion 36 is fitted with a cap plate 68 having a small central opening 70 and a lifting book 72 fixed thereto to facilitate handling. The cap plate 68 is secured by suitable studs 74 and nuts 76, or quick release means may be used if necessary.

lnuse, metal blanks of suitable size are placed over the die blocks 28 and 30 and can be aligned by conventional tooling pins if needed, the arrangement being well known. It should be noted that the blanks can be flat as at 78, or partially preformed as at 89, according to the complexity of the formed part. The cavity 24 has a small outlet 82 leading to an external connection 84, which is connected by a hose 86 to a source of vacuum so that said cavity can be evacuated. The vacuum is necessary to prevent trapped air from forming bubbles or pockets in the formed parts. The pressure dome 32 is seated over the base block 18 and clamped tightly in place, the sealing ring 48 sealing the periphery of the base block when the vacuum is applied. A prepared explosive charge 88 is placed in the pressure dome 32 at a predetermined distance above the diaphragm 44, the exact positioning of the charge being dependent on the size of the charge, the area of the diaphragm and the nature of the parts to be formed. The explosive charge 88 is preferably electrically initiated and can conveniently be suspended in the fluid 66 by means of its firing cord 90, which extends through the opening 70 and is connected to a simple firing circuit diagrammatically illustrated as containing a battery 92 and switch 94, the means for detonating the charge being variable. The charge may be held in place by a wire frame or similar support, or can be supported by tying or clipping the firing cord to the lifting hook 72 or other convenient structure. The cap plate 68 may be removed to facilitate insertion of the explosive charge 88, if the charge is too large to pass through the opening 70.

When the switch 94 is closed, the explosive charge 88 is fired, the resultant explosion distending the diaphragm 44 downwardly with extremely high energy and forcing the blanks 78 and 84] around and into their respective die blocks 28 and 30. The fluid 66 acts as a pressure transmission medium and spreads the explosive force evenly over the diaphragm 44, in addition to controlling the explosion. A pecularity of such explosive charges is that the explosive force tends to be greater in a downward direction, a factor which adds to the effectiveness of the operation. It has been found in tests that a certain optimum depth of fluid above the explosive charge 88 will contain the explosion to the extent that the result is little more than a surface disturbance. The required depth of fluid varies with the size of charge, but for all normal usage is not excessive and may be contained in a vessel or dome of reasonable size. The cap plate 68 is used to prevent any inadvertent loss of fluid upwardly while still providing a vent, although it may be found that the cap plate is unnecessary. The structure is shown installed in a shallow pit 12 in view of the possibility of sudden fluid loss due to bursting of the diaphragm 44, but this is a safety precaution and rupture of the diaphragm is unlikely to occur in normal use.

It has been found in tests that the explosive force will form complex parts without distortion or wrinkling and within very close tolerances, even in materials which are normally considered difiicult to'form by other methods. The forming pressure developed is much greater than that obtained in even the largest forming presses or similar tools, yet is of such extremely short duration that the strength requirements of the pressure dome 32 and other parts of the structure are not particularly severe.

It should be understood that the base block 18, as illustrated, is merely an example of a suitable arrangement for forming multiple small parts. The base block may be made to form a single large part, the cavity 24 itself comprising the die and being suitably shaped. 'Also, the pressure dome 32 need not be a complete unit in itself, but can be a part of a large tank or pit in which the base block and diaphragm assembly are submerged in fluid. As an added feature, the apparatus can be used for blanking or piercing by substituting suitable sharp edged blanking dies of shallow depth for the die blocks.

The apparatus provides an effective method of forming 'many different types of shaped components at high speed with a minimum of equipment. Many components such as used in aircraft must be formed in large, complex presses with matched dies which are costly to make; Often several operations are necessary to form a single part in stages, since certain materials tend to crack if distorted beyond certain limits at the relatively slow speed obtained in a press. Also, at slow forming speeds, the material retains certain spring back properties which must be allowed for in working to close tolerances. At the extreme speeds obtained with high energy explosive forming, the part is formed so suddenly that the material seems to flow into shape with no tendency to crack or spring back. At a comparison, a press may form a part in one tenth of a second or more, whereas the high energy apparatus described herein performs the operation in one three-thousandth of a second, the precise figures being variable.

The explosive charge 88 may be of any suitable type, such as a small quantity of dynamite with a suitable detonator, a specially made capsule of explosive having its own firing means, or even a conventional cartridge with an electrically released firing pin.

' The operation of this invention will be clearly comprehended from a consideration of the foregoing description of the mechanical details thereof, taken in connection with the drawings and the above recited objects. It will be obvious that all said objects are amply achieved by this invention.

It is understood that minor variation from the form of the invention disclosed herein may be made without departure from the spirit and scope of the invention, and that the specification and drawings are to be considered as merely illustrative rather than limiting.

.We claim:

High energy forming apparatus, comprising:

(A) a block having-a forming cavity having a sealing face at the upper portion thereof: a plurality of forming dies positioned at the bottom of said cavity to receive a work piece to be shaped positioned on each said forming dies;

(B) a tubular pressure chamber having a peripheral flange at its lower end; a disc-like flexible resilient diaphragm, having a diameter substantially equal to that of said flange positioned on the lower surface of said flange substantially coextensive with said flange; a retaining ring, having substantially the same dimensions as said flange, positioned on the lower surface of said diaphragm substantially coextensive with said flange; a sealing ring, having substantially the same dimensions as said flange, positioned on the lower surface of said retaining ring substantially coextensive therewith; means for attaching said retaining ring, said sealing ring, said diaphragm, and said flange to form a substantially unitary leakproof structure; a fluid positioned in said pressure chamber; an explosive positioned in said fluid; an end cap positioned at the upper end of said tubular pressure chamber to substantially sealit; (C) means for detonating said explosive;

(D) means for releasably attaching said flange, diaphragm, and ring assembly to said sealing face in a leakp'roof manner, whereby when said explosive is detonated, the shock wave produced in said fluid distends said diaphragm so that it shapes said work. pieces around said forming dies, and when said shock wave subsides the resiliency of said diaphragm causes it to return to its original position and contain said fluid in said pressure chamber;

(E) means permitting the insertion of a new explosive charge into said fluid, said means comprising an opening in said end cap; and

(.F) means on said end cap, for use in lifting said pressure chamber, said contained fluid and said dia phragm-ring assembly from said sealing face of said cavity, whereby new work pieces and if desired new dies may be readily placed in said cavity and-said.

References Cited in the file of this patent .UNITED STATES PATENTS Heacock Apr. 3, 1923 Guerin Oct. 18, 1938 Waters Mar. 9, 1943 Kemerer Sept. 18, 1945 Watter et al Aug. 19, 1958 OTHER REFERENCES American Machinist, June 15, 1959; pp. 127-138; vol, 103; No. 12.

Steel, Aug. 25, 1958; pp. 82-86. 

